The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Contacting devices, which can also be called vertical test cards, essentially comprise a contact head, which bears the test contacts, (also called contact elements), and a connecting device (connector or connector head), which produces the electrical connection between the test contacts and a testing device (tester). The contact head is mounted on the connecting device. The ends of the test contacts that face the contacting device touch contact surfaces of the connecting device. The ends of the test contacts that face away from the connecting device touch contact a test specimen, in particular a wafer. Thus overall it is possible by means of the testing device to produce electrical connection paths to the test specimen and to test the latter for electrical function. The connecting device (connector) preferably comprises a printed circuit board and where necessary a so-called stiffener, that is, a stiffening element, that can absorb the contacting forces when the test specimen is contacted without the printed circuit board becoming bent. The printed circuit board has the aforesaid contact surfaces, that is, the test contacts of the contact head can contact the corresponding contact surfaces of the printed circuit board directly. This is also known as the “direct attach” structure. Alternatively it is also possible for the printed circuit board to be contacted by the test contacts via intermediate wires that are used for routing. This is called a wired connecting head, that is a wired connecting device that is also known as a “wired connector”. The area (contact surface) to be contacted on the connecting device is very small. In particular it has a diameter between 50 μm and 300 μm. This small diameter is due to the fact that the test contacts are very close to one another, for instance at mean intervals ranging from 50 μm to 250 μm, corresponding to the arrangement of the pads (contact pads) to be contacted on the test specimen, in particular a wafer. The arrangement of the contact surfaces on the connecting device, in particular the printed circuit board (PCB), is the same as the corresponding contact pad arrangement on the test specimen, in particular a wafer, up to any minor differences that are present due to the smallest possible incline of the test contacts. However, if the test contacts do not run on an incline but rather are aligned vertically, the mean intervals from the contact pads to the test specimen are approximately equal to the mean intervals from the contact surfaces to the connecting device. In order now to be able to electrically connect the aforesaid testing device to the connecting device, the connecting device takes on an increase in the contact intervals in that its contact surfaces associated with the test head lead to contact surfaces that are far enough apart from one another that can be connected to the testing device with no problem. The contact surfaces that contact the test contacts are preferably disposed on the one side of the printed circuit board and the contact surfaces that contact the testing device are disposed on the other side of the printed circuit board.
All of the information in the foregoing applies to known contacting devices and also to contacting devices for the invention. It is clear that touch contacting the test contacts (contact elements) to the associated contact surfaces of the connecting device can be problematic when there is no alignment but rather for instance all of the test contacts or individual test contacts are positioned offset to the associated contact surfaces on the connecting device, that is, no electrical contacting is attained. This offset can be caused for instance due to variations in temperature.